1. Field of the Invention
The present invention generally relates to wheel track scrapers for use with irrigation systems, and more particularly for use in leveling or erasing the track ruts created in an irrigated field by the wheels of irrigation support towers.
2. Background Information
One of the more common forms of irrigating agricultural fields is the use of what is commonly know as the pivot irrigation system. In the typical pivot irrigation system, a water riser is located in the center of the field and is connected by some sort of slip ring assembly to an irrigation line which extends radially out and is supported by a plurality of support towers. A plurality of sprinkler heads of one form or another, typically impact sprinklers, are fitted to the irrigation line at spaced intervals to deliver irrigation water to the field below as the irrigation line rotates about the central riser. Water is supplied through a pumping system up through the riser to the irrigation line.
The support towers are typically provided with a pair of drive wheels in tandem. Each support tower is also provided with an electric motor which drives a shaft through a gear box to supply power to the wheels for rotation.
Most pivot tower irrigation systems have the capability of being driven in either direction around the riser. This is an essential feature in fields of odd configuration or there is an obstruction which precludes full circle rotation. And, this is a most useful feature, either for rewatering certain parts of the field, or for aligning the pivot in a specific location in the field, either for maintenance purposes, or in preparation for other field work.
Also, the drive systems are either used to incrementally advance the pivot towers or pivot around the field as irrigation is in process, or are capable of driving the pivot around the field at a constant, but albeit very slow, rate of speed.
The net result is that the tower wheels ride in the same wheel tracks over and over again whether operating in only one direction or in both directions.
In addition to pivot irrigation systems, there are found in practice, line irrigation systems which use similar towers to support an overhead irrigation line which travels in a straight line back and forth across the field with the water supplied through some sort of mechanism alongside of the field. Again, as in the case of a pivot irrigation system, the wheels for the support towers ride continuously in the same track.
Irrespective of what type of overhead irrigation system is used, either the pivot or the line systems, the ground underneath the support towers is wet, soft, and muddy. Since the irrigation systems have considerable weight, the inevitable result is that some of the soft, muddy dirt underneath the irrigation support tower wheels is pushed out or displaced by the wheels, and in short order, a wheel rut is formed from the wheel track.
Having these ruts in the field is undesirable for a number of good reasons. These wheel ruts can serve the unwanted function as irrigation channels which can cause erosion, and runoff of irrigation water from higher portions in the field into lower portions, thus causing uneven irrigation. Additionally, after a growing season of using the pivot irrigation system, the wheel ruts can become quite deep and can cause damage to other equipment working in the field. For example, they can damage harvesting equipment such as tractors, grain combines, and trucks.
And finally, the ruts can cause damage to the sprinklers systems themselves, in that as the wheel ruts deepen it takes more power to move the pivot towers, thereby stressing the motors and gearboxes. Additionally some wheels my spin while others have traction, causing misalignment and damaging the irrigation line.
As a result, it is important to minimize the depth of the wheel ruts caused by the tracking of the irrigation support towers. At least one such attempt has been patented as U.S. Pat. No. 5,095,997 to Warner et al., for floating track erasers. This is a device which is towed behind a tractor and is not suitable for use in many fields with growing crops, for example, a crop of standing corn, since the tractor would be driving across the rows of corn, causing substantial crop damage.
Another attempt is found in U.S. Pat. No. 4,909,334 to Tanner et al., for a machine for filling ruts in agricultural fields. Again, this device is used in conjunction with a tractor, its use of a 3-point hitch, and the power takeoff devices to rotate the tines. Again, it is not suitable for use except before the crop is planted or after it has been harvested.
There have been other attempts to provide for a wheel track scraper which is attached directly to the pivot towers. There are two known to the inventor. The first is the disk type, where a pair of rotating disks similar to those used for standard field disking operations are attached to some sort of a frame, and towed behind the tower, with the disks cutting the dirt displaced by the tower wheels, and returning generally it to its original location. This prior art solution is not satisfactory for a number of reasons, which include at least the following. First, the disks are cutting at all times when the tower is moving, and are very effective at moving dirt, and will actually mound it up on the wheel track, and with extended use may actually create a mound on the wheel track where it should be flat, causing the pivot towers to slide off which causes considerable strain to the pivot towers and their drive systems. In practice, these disk type levelers need regular adjustment to avoid building a mount in the wheel tracks. Also, the disks cut small ditches as they constantly cut in the same place each time the irrigation system moves down the track, and these small ditches oftentimes form unwanted irrigation ditches, which, on a slope, can cause erosion. And finally, the disk systems are only capable of being driven in one direction only, since the disks are angled to each other. Thus, if a farmer were to use a disk system to fill the wheel ruts, the farmer loses the capability of moving the pivot irrigation system in both directions. The farmer losses another capability with the disk type system, namely the ability to cross bridges which are often required to span irrigation canals. Obviously, with a line irrigation system which travels back and forth in a straight line, disks used to fill the wheel ruts are not suitable.
The second prior art attempt to scrape the wheel ruts smooth again that is known to the inventor is the use of a drag sled which is attached to the tower frame by use of chains. It simply drags, of its own weight, behind the wheels in an attempt to push some of the displaced dirt back into the wheel ruts. When the farmer reverses the direction of travel, the trailing wheel becomes the lead wheel, and the wheels run over the sled, hopefully to trail behind the new trailing wheel. Unfortunately, these systems are not reliable and oftentimes it is not uncommon for the chain to bind a wheel of the drive system of the tower, causing significant damage to the sprinkler system. When a wheel binds it can also cause misalignment and cause the irrigation line to bend or break. And finally, like the disk type systems, sled type systems cannot be readily used in fields having bridges over canals.
What is needed is a wheel track scraper which is truly capable of pushing the displaced dirt back into the wheel rut to create a truly flat wheel track, without creating any unwanted mounds of dirt and/or collateral side ditches. What is also needed is a wheel track scraper, with no external power supply, which is mounted to the irrigation system in such a manner that it will not bind with it or create undo stress on the drive system for the support towers. These are objects of the invention.
Another object of the invention is to provide, in at least one embodiment, a wheel track scraper incorporating the features set forth above and is also fully operable and capable of use in either direction of travel.
These objects are achieved in a wheel track scraper which is attached to a tower frame member of a pivot tower. The wheel track scraper is provided with an attachment bracket which is comprised of a vertical rod attached to a cross bar. The cross bar is in turn attached to the tower frame member by means of a frame plate and u-bolts. This only one of a number of ways of affixing the attachment bracket to the pivot tower, others including welding, bolting, or even forming as an integral piece of the support tower. The vertical rod in the preferred embodiment is height adjustable in relationship to the cross bar to accommodate different heights for the frame member and different diameter tire sizes.
Attached to the vertical rod below the frame member are a pair of pivot arms. The lower pivot arm is supported in the horizontal position by means of a stop bar which is firmly attached to the vertical rod and provides for a preset lowest elevation for the rest of the attachment mechanism and the scraper arms. The upper pivot arm is spring loaded, to urge the upper and lower pivot arms down against the stop bar, yet still provide for some upward travel in the event that either or both scraper bars encounter an obstacle in the wheel track.
In the preferred embodiment, the remainder of the attachment bracket assembly is formed of a pair of horizontal support bracket receivers and scraper bar brackets which interconnect with a pair of scraper blades. In the preferred embodiment, the scraper bar brackets are both offset adjustable and width adjustable within the horizontal support bracket receivers to provide for the spacing of the scraper blades to accommodate different size wheel widths on various pivot tower configurations, and even for different field conditions as may be the case.
In the preferred embodiment, the pair of opposing scraper blades are each formed of two blade portions which are joined together at an angle with an apex in the central portion of the scraper blades. This enables to operator to move the irrigation system in both directions, forward and reverse equally well. In the second embodiment, only a first set of opposing blade portions are used with the second omitted. In this embodiment, the wheel track scraper is only usable in one direction of travel.
In the preferred embodiment, the attachment bracket is positioned so as to locate the scraper blades on the inside between the tandem wheels of the tower, closer to one or the other of them. The reason for positioning the blades close to the wheel is that is minimizes the variations in elevation of the scraper blade vis-à-vis the elevation of the wheel. However it should be apparent to those skilled in the art that the opposing scraper blades could also be positioned in front of, or behind, or even equidistant between two wheels.
In use, first and second scraper blade assemblies will push, either using the first or second portions of the scraper blades, and displace dirt back into the track to fill in the wheel rut as the wheels of the pivot tower move. Also, in practice, no significant mounding occurs as is the case with the prior art disking systems, nor are there any collateral side ditches formed by disk cutting into the dirt, even when there is no wheel rut to fill. In the present invention, if there is no displaced dirt, the scraper blades simply track along with the wheel and do not engage the ground in any significant manner.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description wherein I have shown and described only the preferred embodiment of the invention, simply by way of illustration of the best mode contemplated by carrying out my invention. As will be realized, the invention is capable of modification in various obvious respects all without departing from the invention. Accordingly, the drawings and description of the preferred embodiment are to be regarded as illustrative in nature, and not as restrictive.